1. Field of the Invention
The present invention is related to a recording medium storing a map information, a map information processing device for processing the map information, a map information processing system, a map information processing method, a map information processing program and a recording medium storing the map information processing program, the map information representing a road in a manner such that a pair of point information is connected with a segment information.
2. Description of Related Art
A communication navigation systems conventionally known are that acquires map information stored in sever units via communication by using mobile communication terminals such as an in-vehicle or portable navigation device, a PDA (Personal Digital Assistant), a mobile phone, a PHS (Personal Handyphone System), and a portable personal computer so as to search for information on a current position and a route to a destination, and to retrieve information on shops nearby. In such communication navigation system, since the management of map information with a large amount of data is centralized at the server unit, the mobile communication terminal need not to have a storage for storing the map information, thereby simplifying the structure, reducing in the size and the weight and readily providing the latest map information. For the purpose of smooth operation and management of the data, the map information is constituted by a plurality of digitalized map files that are divided into a plurality of areas.
A display data including an element data for an element consisting of a map is generally used when the map is displayed on a display. In other words, the display data dedicates to smoothly display the map. In a navigation system, when overlaying a current position of a vehicle onto a displayed map, a map matching processing is performed in order to display the current position in a manner such that the vehicle travels on a road in the map. It is known that the map matching processing is also performed, with the use of matching data where a road is represented by point information and segment information that connects the point information, in order to correct the current position on the basis of the matching data and the current position of the vehicle separately measured and overlay the corrected current position onto the map displayed by the display-oriented data.
A structure performing the map matching processing, however, needs both of the display data and the matching data, thus the amount of the processing data may be considerably large and a processing efficiency might not be improved.
With respect to the above problem, the data amount of the accumulating map information is tried to be reduced in order to reduce a processing load of a server unit and to simplify a structure thereof (see the right column on page 5 to the right column on page 41, Japanese Examined Publication No.3332225). In the above prior art, map files adjoining each other has a connection relationship by way of matching coordinates of nodes in adjoining positions of the map file, each node being an information for a road on the map file. Therefore, the data amount of connection nodes representing the connection relationship of the adjoining map files can be reduced.
Though the prior art reduces the data amount of the connection relationship of the map file, the data amount of the map file distributed to the mobile communication terminal, itself is hardly reduced. Therefore, a load for sending/receiving the map file to the mobile communication terminal and the processing load of the map file at the mobile communication terminal might not be reduced.
It is, therefore, required to reduce the information amount of the map information.
When the information amount of the map information is reduced too much, another problem may be raised, for instance, a display speed being slow, or specific and desired information being unavailable.